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    Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
    different chromosomes.
    One gene controls the pigment colour. The presence of allele A results in a yellow and black
    banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
    the genotype aa do not make the yellow pigment and are, therefore, black.
    The other gene determines whether any pigment is produced. The allele D is required for
    development of coat colour. Mice with the genotype dd produce no pigment and are called
    albino.

    Question : Give all the possible genotypes for a black mouse.

    I don't know how to work this out
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    (Original post by FREYA2898)
    Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
    different chromosomes.
    One gene controls the pigment colour. The presence of allele A results in a yellow and black
    banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
    the genotype aa do not make the yellow pigment and are, therefore, black.
    The other gene determines whether any pigment is produced. The allele D is required for
    development of coat colour. Mice with the genotype dd produce no pigment and are called
    albino.

    Question : Give all the possible genotypes for a black mouse.

    I don't know how to work this out
    A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
    So answer would be, AA, AA, Aa.
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    (Original post by FREYA2898)
    Coat colour in mice is controlled by two genes, each with two alleles. The genes are on
    different chromosomes.
    One gene controls the pigment colour. The presence of allele A results in a yellow and black
    banding pattern on individual hairs, producing an overall grey appearance called agouti. Mice with
    the genotype aa do not make the yellow pigment and are, therefore, black.
    The other gene determines whether any pigment is produced. The allele D is required for
    development of coat colour. Mice with the genotype dd produce no pigment and are called
    albino.

    Question : Give all the possible genotypes for a black mouse.

    I don't know how to work this out
    You simply need to list each possible combination of A,a,D and d, that give rise to a black mouse.

    You might like to break this down into first considering what affects the banding pattern, and then what affects pigment i.e. consider the A,a gene first, then the D,d gene.


    (Original post by TheFactor)
    A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
    So answer would be, AA, AA, Aa.
    Erm, you might wanna re-read the question. . . aa gives rise to black.
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    Oh, must've got it wrong. I hastily answered it while trying to hold my bladder before going to the toilet.
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    (Original post by TheFactor)
    A and D are dominant alleles. AA, Aa and AA would all result in black, aa would result in it being yellow as it is recessive.
    So answer would be, AA, AA, Aa.

    Thanks for answering but I found the answer now
    (ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;;(allow 1 mark for 2 or 3 correct answers)
    I still don't know how you get this
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    (Original post by TheFactor)
    Oh, must've got it wrong. I hastily answered it while trying to hold my bladder before going to the toilet.
    Thanks for answering but I found the answer now (ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;; (allow 1 mark for 2 or 3 correct answers)
    I still don't know how you get this
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    (Original post by FREYA2898)
    Thanks for answering but I found the answer now (ii) a^ha^h BB, a^haBB, a^ha^h Bb, a^haBb;; (allow 1 mark for 2 or 3 correct answers)
    I still don't know how you get this
    What is the superscript h notating?
    It's been a while since I did stuff like this but the only thing I remember a superscript for was sex-linked alleles. Also your D has morphed into a B.

    It should be clear that you need two recessive alleles, aa to get a black mouse from the description given.
    So you can fix the first two letters in the genotype aa and then you can find the alleles of the other gene in the normal way.
 
 
 
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